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Photosynthetic organisms use huge arrays of pigments to draw light energy into the core of photosystem II. The arrangement of these pigments influences how much energy reaches the reaction center. Pi et al. determined the structure of photosystem II from a diatom in complex with an antenna of fucoxanthin–chlorophyll a/c binding proteins (FCPs) (see the Perspective by Büchel). The specialized pigments in this complex allow microalgae to harvest light within a wide range of the visible spectrum. The FCPs are arranged in a pattern analogous to light-harvesting complexes in plants. Science , this issue p. eaax4406 ; see also p. 447 The cryo-EM structure of a diatom photosystem II complex suggests energy transfer and dissipation pathways. Diatoms play important roles in global primary productivity and biogeochemical cycling of carbon, in part owing to the ability of their photosynthetic apparatus to adapt to rapidly changing light intensity. We report a cryo–electron microscopy structure of the photosystem II (PSII)–fucoxanthin (Fx) chlorophyll (Chl) a/c binding protein (FCPII) supercomplex from the centric diatom Chaetoceros gracilis . The supercomplex comprises two protomers, each with two tetrameric and three monomeric FCPIIs around a PSII core that contains five extrinsic oxygen-evolving proteins at the lumenal surface. The structure reveals the arrangement of a huge pigment network that contributes to efficient light energy harvesting, transfer, and dissipation processes in the diatoms.

P2X7 receptor (P2X7R) plays a role in regulating tumor progression, but it is unclear whether P2X7R affects the pathological characteristics of patients with gastric cancer and the activity of gastric cancer cells. Therefore, this study preliminarily investigated the relationship between P2X7R and clinicopathological features of patients with gastric cancer, and further explored the effect of P2X7R on the proliferation, migration and invasion of gastric cancer cells through functional experiments. The results showed that P2X7R was highly expressed in gastric cancer tissues and gastric cancer cells. High expression of P2X7R was closely related to lymphatic metastasis, vascular invasion and Tumor-Node-Metastasis (TNM) stage in patients with gastric cancer. High expression of P2X7R predicted poor overall survival in patients. Moreover, the activation of P2X7R by ATP and its analogue BzATP increased the calcium current of gastric cancer cells, enhanced YF actin stress and cell viability, and promoted the proliferation, migration and invasion of gastric cancer cells. While P2X7R antagonists (A438079 and AZD9056) inhibited the proliferation, migration and invasion of gastric cancer cells induced by ATP. Therefore, the data obtained in this experiment suggest that P2X7R may be another potential molecular target for the prevention and treatment of gastric cancer.

Photosystem I (PSI) is one of the two photosystems present in oxygenic photosynthetic organisms and functions to harvest and convert light energy into chemical energy in photosynthesis. In eukaryotic algae and higher plants, PSI consists of a core surrounded by variable species and numbers of light-harvesting complex (LHC)I proteins, forming a PSI-LHCI supercomplex. Here, we report cryo-EM structures of PSI-LHCR from the red alga Cyanidioschyzon merolae in two forms, one with three Lhcr subunits attached to the side, similar to that of higher plants, and the other with two additional Lhcr subunits attached to the opposite side, indicating an ancient form of PSI-LHCI. Furthermore, the red algal PSI core showed features of both cyanobacterial and higher plant PSI, suggesting an intermediate type during evolution from prokaryotes to eukaryotes. The structure of PsaO, existing in eukaryotic organisms, was identified in the PSI core and binds three chlorophylls a and may be important in harvesting energy and in mediating energy transfer from LHCII to the PSI core under state-2 conditions. Individual attaching sites of LHCRs with the core subunits were identified, and each Lhcr was found to contain 11 to 13 chlorophylls a and 5 zeaxanthins, which are apparently different from those of LHCs in plant PSI-LHCI. Together, our results reveal unique energy transfer pathways different from those of higher plant PSI-LHCI, its adaptation to the changing environment, and the possible changes of PSI-LHCI during evolution from prokaryotes to eukaryotes.

Diatom is an important group of marine algae and contributes to around 20% of the global photosynthetic carbon fixation. Photosystem I (PSI) of diatoms is associated with a large number of fucoxanthin-chlorophyll a / c proteins (FCPIs). We report the structure of PSI-FCPI from a diatom Chaetoceros gracili s at 2.38 Å resolution by single-particle cryo-electron microscopy. PSI-FCPI is a monomeric supercomplex consisting of 12 core and 24 antenna subunits (FCPIs), and 326 chlorophylls a , 34 chlorophylls c , 102 fucoxanthins, 35 diadinoxanthins, 18 β -carotenes and some electron transfer cofactors. Two subunits designated PsaR and PsaS were found in the core, whereas several subunits were lost. The large number of pigments constitute a unique and huge network ensuring efficient energy harvesting, transfer and dissipation. These results provide a firm structural basis for unraveling the mechanisms of light-energy harvesting, transfer and quenching in the diatom PSI-FCPI, and also important clues to evolutionary changes of PSI-LHCI. Diatoms are marine algae with an important role in global photosynthetic carbon fixation. Here, the authors present the 2.38 Å cryo-EM structure of photosystem I (PSI) in complex with its 24 fucoxanthin chlorophyll a/c -binding (FCPI) antenna proteins from the diatom Chaetoceros gracilis , which provides mechanistic insights into light-energy harvesting, transfer and quenching of the PSI-FCPI supercomplex.

Nuclear pore complexes (NPCs) mediate bidirectional nucleocytoplasmic transport of substances in eukaryotic cells. However, the accurate molecular arrangement of NPCs remains enigmatic owing to their huge size and highly dynamic nature. Here we determined the structure of the asymmetric unit of the inner ring (IR monomer) at 3.73 Å resolution by single-particle cryo-electron microscopy, and created an atomic model of the intact IR consisting of 192 molecules of 8 nucleoporins. In each IR monomer, the Z-shaped Nup188–Nup192 complex in the middle layer is sandwiched by two approximately parallel rhomboidal structures in the inner and outer layers, while Nup188, Nup192 and Nic96 link all subunits to constitute a relatively stable IR monomer. In contrast, the intact IR is assembled by loose and instable interactions between IR monomers. These structures, together with previously reported structural information of IR, reveal two distinct interaction modes between IR monomers and extensive flexible connections in IR assembly, providing a structural basis for the stability and malleability of IR.

Photosystem I (PSI) is a highly efficient natural light-energy converter, and has diverse light-harvesting antennas associated with its core in different photosynthetic organisms. In green algae, an extremely large light-harvesting complex I (LHCI) captures and transfers energy to the PSI core. Here, we report the structure of PSI–LHCI from a green alga Bryopsis corticulans at 3.49 Å resolution, obtained by single-particle cryo-electron microscopy, which revealed 13 core subunits including subunits characteristic of both prokaryotes and eukaryotes, and 10 light-harvesting complex a (Lhca) antennas that form a double semi-ring and an additional Lhca dimer, including a novel four-transmembrane-helix Lhca. In total, 244 chlorophylls were identified, some of which were located at key positions for the fast energy transfer. These results provide a firm structural basis for unravelling the mechanisms of light-energy harvesting, transfer and quenching in the green algal PSI–LHCI, and important clues as to how PSI–LHCI has changed during evolution. Structure of the photosystem I–light-harvesting complex I in green alga at 3.49 Å resolution shows 13 core subunits and 10 antennas in a double semi-ring. This provides a basis for unravelling the mechanisms of algal light-energy harvesting.

Plants harvest light energy utilized for photosynthesis by light-harvesting complex I and II (LHCI and LHCII) surrounding photosystem I and II (PSI and PSII), respectively. During the evolution of green plants, moss is at an evolutionarily intermediate position from aquatic photosynthetic organisms to land plants, being the first photosynthetic organisms that landed. Here, we report the structure of the PSI–LHCI supercomplex from the moss Physcomitrella patens (Pp) at 3.23 Å resolution solved by cryo-electron microscopy. Our structure revealed that four Lhca subunits are associated with the PSI core in an order of Lhca1–Lhca5–Lhca2–Lhca3. This number is much decreased from 8 to 10, the number of subunits in most green algal PSI–LHCI, but the same as those of land plants. Although Pp PSI–LHCI has a similar structure as PSI–LHCI of land plants, it has Lhca5, instead of Lhca4, in the second position of Lhca, and several differences were found in the arrangement of chlorophylls among green algal, moss, and land plant PSI–LHCI. One chlorophyll, PsaF–Chl 305, which is found in the moss PSI–LHCI, is located at the gap region between the two middle Lhca subunits and the PSI core, and therefore may make the excitation energy transfer from LHCI to the core more efficient than that of land plants. On the other hand, energy-transfer paths at the two side Lhca subunits are relatively conserved. These results provide a structural basis for unravelling the mechanisms of light-energy harvesting and transfer in the moss PSI–LHCI, as well as important clues on the changes of PSI–LHCI after landing.

Background: The incidence of acute myocardial infarction (AMI) in the younger population has been increasing gradually in recent years. The objective of the present study is to investigate the safety and effectiveness of drug-eluting balloons (DEBs) in young patients with AMI. Methods: All consecutive patients with AMI aged ≤ 45 years were retrospectively enrolled. The primary endpoint was a device-oriented composite endpoint (DOCE) of cardiac death, target vessel myocardial infarction (MI), or target lesion revascularization (TLR). The secondary study endpoints included heart failure and major bleeding events. Results: A total of 276 young patients presenting with AMI were finally included. The median follow-up period was 1155 days. Patients treated with DEBs had a trend toward a lower incidence of DOCEs (3.0% vs. 11.0%, p = 0.12) mainly driven by the need for TLR (3.0% vs. 9.1%, p = 0.19) than those treated with DESs. No significant differences between the two groups were detected in the occurrence of cardiac death (0.0% vs. 0.5%, p = 0.69), MI (0.0% vs. 1.4%, p = 0.40), heart failure (0.0% vs. 1.9%, p = 0.39), or major bleeding events (1.5% vs 4.8%, p = 0.30). Multivariate regression analysis showed that DEBs were associated with a trend toward a lower risk of DOCEs (HR 0.13, 95% CI [0.02, 1.05], p = 0.06). Conclusions: The findings of the present study suggested that DEBs might be a potential treatment option in young patients with AMI. A larger scale, randomized, multicenter study is required to investigate the safety and effectiveness of DEBs in this setting.

We herein describe a 33-year-old woman with a mechanical aortic and mitral valve who developed repetitive monomorphic ventricular tachycardia with unstable hemodynamics. Catheter ablation by direct puncture at the left ventricular apex through a minithoracotomy successfully terminated the ventricular tachycardia, which had originated from the apical-septal endocardium in the left ventricle, despite the hindrance to routine access. No procedure-related complications or recurrence of the clinical ventricular tachycardia developed during a 66-month follow-up, demonstrating that endocardial ablation through direct cardiac cavity puncture can be considered in select cases.

Neuropathic pain (NPP) is caused by damage to the somatosensory nervous system. Its prominent symptoms are spontaneous pain, hyperalgesia and abnormal pain. This pain is long-lasting and unbearable, seriously affecting the patient’s quality of life. At present, the clinical treatment effect of painkillers to relieve NPP is still not ideal, nor can it repair damaged nerves and achieve long-term treatment results. In recent years, the application of cell therapy strategies in the field of pain has yielded encouraging results, including preclinical studies and clinical trials. Mesenchymal stem cells (MSCs) are pluripotent progenitor cells derived from mesogenesis. They have the ability to self-renew and differentiate into multiple cell types and have been widely studied and applied in the field of neuroregenerative medicine. MSCs play an important mechanism functional role in promoting injured nerve regeneration and pain relief by regulating multiple processes in target cells, including immunoregulation, anti-inflammatory properties, promoting axon regeneration and re-myelination, promoting angiogenesis, and secreting neurotrophic factors. Moreover, MSCs can also release exosomes, which may be part of their analgesic effects. Exosomes derived from MSC also have the functional properties of mother cells and have therapeutic potential for treating NPP by promoting cell proliferation, regulating inflammatory responses, reducing cell death, promoting axon regeneration and angiogenesis. Therefore, in this article, we discussed current treatment strategies for NPP and explored the functional role and mechanism of MSCs in the treatment of NPP. We also analyzed the current problems and challenges in the application of MSCs in clinical trials of NPP.